The most significant cognitive bias afflicting us humans is optimism bias. According to Daniel Kahenman, "....most of us view the world as more benign than it really is, our own attributes as more favorable than they truly are, and the goals we adopt as more achievable than they are likely to be. We also tend to exaggerate our ability to forecast the future, which fosters overconfidence."

Could there be a nicer form of affliction? But it is dangerous. And there is optimism bias and then there is well-groomed gullibility. Which characterized the FacebookIPO and why does it matter?

When Facebook (FB) went to IPO very few people were calling it a well-crafted bubble (though there were exceptions). It was only after the IPO failed to take off that talk of market manipulation sprang up - overnight! Since then its become an established fact that the bubble was indeed carefully crafted by Facebook's bankers. So here's the question - why did we bottle this in advance of the IPO, why didn't we call it for what it was? Plenty of us felt it.

And there were certainly plenty of clues - like GM withdrawing its ads a day before the IPO, and Facebook's acknowledgement that it was struggling to sell ad inventory to mobile accounts, Zuckerberg's disrespectful dress code. After the IPO there were some stringent views: "On Friday, like most of you, I watched the nation's media help to perpetrate one of the great frauds in American history.," said The Street, under a heading The Big Lie of The Facebook IPO.

But that still begs the question why a lot of us let ourselves be complicit in what Facebook and its bankers were doing - grooming us.The point is not to deny optimism bias - but simply to say if you work as an analyst or journalist or commentator, you're supposed to work around optimism bias and call things as they are. We seem to be running scared of that duty.

There is also a collective failure of nerve to call the economy more generally, not just Facebook. We are so bought into the notion of growth, progress and prosperity that we can't bear to call out what is clearly happening - a transformation that is impoverishing large segments of the populations of Europe and America, a change that is so pervasive that even companies sitting on huge cash piles they won't spend.

So we're focused instead on telling ourselves stories about a happier place, even when, like the Facebook IPO, they lack credibility.

In the UK, the Governor of the Bank of England said recently, "I don't think we are yet halfway through [the crisis]", adding; "My estimate of how long it will take to recover is expanding all the time." This is an accurate not a pessimistic view of what is going on in the economy. We need to learn quickly how to absorb and respond to it. Yes, that's just half the story - there are some great things going on in the hacker world - but right now it feels like a crime to question optimism. There's plenty of people holding Facebook shares who are bound to say we need to start calling things as they are not as we want them to be.